Pub Date : 2026-03-01Epub Date: 2026-01-27DOI: 10.1016/j.gete.2026.100794
German David Matos-Paucar , Merita Tafili , Jan Machaček , Torsten Wichtmann
The soil–water retention curve (SWRC) is fundamental in geotechnical engineering, influencing the hydraulic and mechanical response of unsaturated soils. This study evaluates three generalised SWRC models that account for density effects and/or hydraulic hysteresis: the Gallipoli, Sun, and Gao formulations. Their simulation performance is assessed against experimental data from a wide range of soils, including compacted till, Pearl clays, Barcelona silt, and silty sands. The analyses highlight the strengths and limitations of each model in reproducing main wetting and drying branches, scanning curves, and density-dependent shifts of the SWRC. Among the tested formulations, the Gao model demonstrates the most robust capability to represent hysteresis and density effects across broad suction ranges. Finally, selected hydraulic models were coupled with the hypoplastic constitutive model proposed by Tafili and Machaček (2023) to evaluate hydro–mechanical interactions of unsaturated soils under various stress and hydraulic conditions, highlighting that the choice of SWRC formulation strongly influences predictions of volumetric response, stiffness evolution, and suction-dependent strength. This underlines the importance of selecting an appropriate SWRC model for reliable hydro–mechanical modelling of unsaturated soils.
{"title":"Evaluation of generalised soil water retention models and their role in hydro–mechanical modelling of unsaturated soils","authors":"German David Matos-Paucar , Merita Tafili , Jan Machaček , Torsten Wichtmann","doi":"10.1016/j.gete.2026.100794","DOIUrl":"10.1016/j.gete.2026.100794","url":null,"abstract":"<div><div>The soil–water retention curve (SWRC) is fundamental in geotechnical engineering, influencing the hydraulic and mechanical response of unsaturated soils. This study evaluates three generalised SWRC models that account for density effects and/or hydraulic hysteresis: the Gallipoli, Sun, and Gao formulations. Their simulation performance is assessed against experimental data from a wide range of soils, including compacted till, Pearl clays, Barcelona silt, and silty sands. The analyses highlight the strengths and limitations of each model in reproducing main wetting and drying branches, scanning curves, and density-dependent shifts of the SWRC. Among the tested formulations, the Gao model demonstrates the most robust capability to represent hysteresis and density effects across broad suction ranges. Finally, selected hydraulic models were coupled with the hypoplastic constitutive model proposed by Tafili and Machaček (2023) to evaluate hydro–mechanical interactions of unsaturated soils under various stress and hydraulic conditions, highlighting that the choice of SWRC formulation strongly influences predictions of volumetric response, stiffness evolution, and suction-dependent strength. This underlines the importance of selecting an appropriate SWRC model for reliable hydro–mechanical modelling of unsaturated soils.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"45 ","pages":"Article 100794"},"PeriodicalIF":3.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-01-13DOI: 10.1016/j.gete.2026.100793
Yang Shen , Baiquan Lin , Minghua Lin , Ting Liu , Tong Liu , Zhiyong Hao , Wei Yang
The fracture zone of abandoned mining sites is prone to Mode-I fractures. In coal rock layers with more aquifers, the erosion and dissolution of abandoned mine water will accelerate this process. To investigate the respective effects and contributions of swelling and erosion on Mode-I fracture in abandoned mine water, this study combines laboratory experiments and discrete element simulations to explore the macro- and micro-fracture processes of samples under the coupled action of erosion and swelling. Five time gradients were set for treating the prepared NSCB samples (0, 7, 14, 21, 30 days), and the degree of deterioration of the Mode-I fracture toughness of the coal samples was explored. A mechanical model for mineral dissolution-swelling was established by combining Computed Tomography(CT) scanning and the discrete element grain-based model (GBM). The Swelling/ dissolution expansion coefficient were defined, by adjusting the expansion coefficient, the model simulates the damage process of coal particles and minerals undergoing dissolution-swelling. The research results indicate that the failure behavior transitions from brittle fracture to ductile fracture. Simulation results indicate that the initial stage of contact between abandoned mine water and coal is primarily characterized by hydraulic swelling, with corrosion starting to affect the sample in the later stages of contact. It is observed that corrosion leads to an increase in transgranular cracks during Mode-I fracture processes, whereas the original sample primarily experiences slip fracture along mineral crystal boundaries.
{"title":"The contribution of physical-chemical effects of abandoned mine water to the deterioration of Mode-I fracture toughness- based on CT-DEM integrated modeling","authors":"Yang Shen , Baiquan Lin , Minghua Lin , Ting Liu , Tong Liu , Zhiyong Hao , Wei Yang","doi":"10.1016/j.gete.2026.100793","DOIUrl":"10.1016/j.gete.2026.100793","url":null,"abstract":"<div><div>The fracture zone of abandoned mining sites is prone to Mode-I fractures. In coal rock layers with more aquifers, the erosion and dissolution of abandoned mine water will accelerate this process. To investigate the respective effects and contributions of swelling and erosion on Mode-I fracture in abandoned mine water, this study combines laboratory experiments and discrete element simulations to explore the macro- and micro-fracture processes of samples under the coupled action of erosion and swelling. Five time gradients were set for treating the prepared NSCB samples (0, 7, 14, 21, 30 days), and the degree of deterioration of the Mode-I fracture toughness of the coal samples was explored. A mechanical model for mineral dissolution-swelling was established by combining Computed Tomography(CT) scanning and the discrete element grain-based model (GBM). The Swelling/ dissolution expansion coefficient were defined, by adjusting the expansion coefficient, the model simulates the damage process of coal particles and minerals undergoing dissolution-swelling. The research results indicate that the failure behavior transitions from brittle fracture to ductile fracture. Simulation results indicate that the initial stage of contact between abandoned mine water and coal is primarily characterized by hydraulic swelling, with corrosion starting to affect the sample in the later stages of contact. It is observed that corrosion leads to an increase in transgranular cracks during Mode-I fracture processes, whereas the original sample primarily experiences slip fracture along mineral crystal boundaries.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"45 ","pages":"Article 100793"},"PeriodicalIF":3.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-01-05DOI: 10.1016/j.gete.2026.100788
Changde Yang , Yang Chen , Binbin Yang
This study introduces the results of evaporation cracking test on soil with different discrete polypropylene fiber content (PPFC). Changes in the cracking characteristics are quantitatively analyzed by using digital image processing technology. The results indicate that the fractal dimension (FD) of the cracking process can be divided into three stages. Stage A is defined as the rapid cracking stage when the rate of cracking increases rapidly with a PPFC of 0.2 %. However, the rate of cracking decreases with further increases in PPFC. In Stage B, the FD of cracks with a PPFC of 0.2 % and 0.7 % tends to be stable at first, while that of cracks with a PPFC less than 0.2 % increases gradually with time. The FD approaches a constant in Stage C and its value decreases with increases in the PPFC. The characteristics of the average moisture content of soil with different PPFC along with the drying time show a close agreement with those when the PPFC is less than 0.2 %. It is found that fibers can restrain the expansion of soil which reduces cracking and evaporation of free water which results in a delay of the evaporation of the bounded water. The 0.2 % PPFC is the optimal ratio for inhibiting Xinjiang clay.
{"title":"Desiccation cracking behavior of discrete fiber mixed with clay material","authors":"Changde Yang , Yang Chen , Binbin Yang","doi":"10.1016/j.gete.2026.100788","DOIUrl":"10.1016/j.gete.2026.100788","url":null,"abstract":"<div><div>This study introduces the results of evaporation cracking test on soil with different discrete polypropylene fiber content (PPFC). Changes in the cracking characteristics are quantitatively analyzed by using digital image processing technology. The results indicate that the fractal dimension (FD) of the cracking process can be divided into three stages. Stage A is defined as the rapid cracking stage when the rate of cracking increases rapidly with a PPFC of 0.2 %. However, the rate of cracking decreases with further increases in PPFC. In Stage B, the FD of cracks with a PPFC of 0.2 % and 0.7 % tends to be stable at first, while that of cracks with a PPFC less than 0.2 % increases gradually with time. The FD approaches a constant in Stage C and its value decreases with increases in the PPFC. The characteristics of the average moisture content of soil with different PPFC along with the drying time show a close agreement with those when the PPFC is less than 0.2 %. It is found that fibers can restrain the expansion of soil which reduces cracking and evaporation of free water which results in a delay of the evaporation of the bounded water. The 0.2 % PPFC is the optimal ratio for inhibiting Xinjiang clay.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"45 ","pages":"Article 100788"},"PeriodicalIF":3.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145926994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The integrity of open-hole wellbores in deep, high-pressure high-temperature (HPHT), and unconventional reservoirs is critically affected by the coupled interactions of mechanical loads, temperature variations, and pore fluid seepage. This Thermo–Hydro–Mechanical (T–H–M) coupling governs the evolution of the near-wellbore stress field and plays a decisive role in maintaining wellbore stability under complex geological conditions However, existing studies often rely on two-dimensional simplifications or slow numerical models, and lack a generalized analytical framework to characterize three-dimensional (3D) asymmetric T–H–M coupling. To address this limitation, this study develops a 3D steady-state analytical solution for the T–H–M coupled near-wellbore stress field in open-hole formations. Using the linear superposition principle, we decompose the coupled system into three independent subproblems… and superimpose their analytical solutions to obtain the total stress field under linearly depth-dependent loads. The results reveal a pronounced non-axisymmetric stress distribution governed by horizontal stress anisotropy, with the maximum circumferential compression occurring in the direction of the minimum horizontal principal stress. Temperature differentials between the drilling fluid and the formation exert a dominant influence on wellbore stability: fluid cooling—occurring when the drilling-fluid temperature is lower than the formation temperature—induces thermal tensile stresses that mitigate compressive stress concentrations and thereby suppress shear failure; in contrast, fluid heating exacerbates compressive stresses and promotes wellbore instability. Seepage-induced tensile stresses near the wellbore wall counteract mechanical and thermal compression, resulting in radial stress reversal in the near-wellbore zone. The proposed analytical solution provides an accurate, computationally efficient, and physically interpretable framework for predicting near-wellbore stress distributions under complex three-dimensional thermal–mechanical–hydraulic coupling conditions; it delivers both theoretical insight and actionable guidance for temperature management, drilling-fluid system optimization, and wellbore integrity design in deep, high-pressure high-temperature, and geothermal drilling applications.
{"title":"A Thermo–Hydro–Mechanical (T–H–M) coupled analytical solution for an open-hole under 3D asymmetric loads","authors":"Weizhe Qiu, Bo Zhou, Xiaotian Li, Jiahao Li, Xudong Zhang, Xiuxing Zhu, Peng Jia","doi":"10.1016/j.gete.2026.100802","DOIUrl":"10.1016/j.gete.2026.100802","url":null,"abstract":"<div><div>The integrity of open-hole wellbores in deep, high-pressure high-temperature (HPHT), and unconventional reservoirs is critically affected by the coupled interactions of mechanical loads, temperature variations, and pore fluid seepage. This Thermo–Hydro–Mechanical (T–H–M) coupling governs the evolution of the near-wellbore stress field and plays a decisive role in maintaining wellbore stability under complex geological conditions However, existing studies often rely on two-dimensional simplifications or slow numerical models, and lack a generalized analytical framework to characterize three-dimensional (3D) asymmetric T–H–M coupling. To address this limitation, this study develops a 3D steady-state analytical solution for the T–H–M coupled near-wellbore stress field in open-hole formations. Using the linear superposition principle, we decompose the coupled system into three independent subproblems… and superimpose their analytical solutions to obtain the total stress field under linearly depth-dependent loads. The results reveal a pronounced non-axisymmetric stress distribution governed by horizontal stress anisotropy, with the maximum circumferential compression occurring in the direction of the minimum horizontal principal stress. Temperature differentials between the drilling fluid and the formation exert a dominant influence on wellbore stability: fluid cooling—occurring when the drilling-fluid temperature is lower than the formation temperature—induces thermal tensile stresses that mitigate compressive stress concentrations and thereby suppress shear failure; in contrast, fluid heating exacerbates compressive stresses and promotes wellbore instability. Seepage-induced tensile stresses near the wellbore wall counteract mechanical and thermal compression, resulting in radial stress reversal in the near-wellbore zone. The proposed analytical solution provides an accurate, computationally efficient, and physically interpretable framework for predicting near-wellbore stress distributions under complex three-dimensional thermal–mechanical–hydraulic coupling conditions; it delivers both theoretical insight and actionable guidance for temperature management, drilling-fluid system optimization, and wellbore integrity design in deep, high-pressure high-temperature, and geothermal drilling applications.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"45 ","pages":"Article 100802"},"PeriodicalIF":3.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146173495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-01-31DOI: 10.1016/j.gete.2026.100797
Brecht B.T. Wassing , Justin Pogacnik , Matsen Broothaers , Loes Buijze , Johannes H.P. de Bresser
The geothermal project at the VITO Sustainability Park in Mol targets the fractured carbonates of the Dinantian formation. During balanced geothermal operations, several earthquakes were recorded, with a maximum magnitude of ML 2.2. To better understand the mechanisms driving this seismicity, we developed a thermo-hydro-mechanical model to simulate pressure, temperature and stress changes on a fault near the injection well, which hosts most of the seismic events. Given the observations of a low stress drop and low seismic moment release, the fault is represented in the model as comprising a few isolated asperities embedded within a broader aseismic zone. Although the model geometry is simplified, and both flow and mechanical behavior are not fully constrained, it shows potential to reproduce the main characteristics of field observations of seismicity at the geothermal site. Our simulations indicate that thermal effects had limited influence on fault stress, primarily due to the relatively small injected volumes. Rate effects - through rapid poroelastic unloading immediately after shut-in – may have facilitated seismogenic slip after shut-in. Aseismic slip, primarily driven by pressure increases, appears to have played a significant role in fault reactivation. The model results suggest that stress transfer from aseismic slip to fault asperities may have been a key driver of seismicity, particularly for larger events occurring at greater depths and farther from the injection well.
{"title":"Mechanisms of induced seismicity due to geothermal operations in the Dinantian fractured carbonates in Mol, Belgium","authors":"Brecht B.T. Wassing , Justin Pogacnik , Matsen Broothaers , Loes Buijze , Johannes H.P. de Bresser","doi":"10.1016/j.gete.2026.100797","DOIUrl":"10.1016/j.gete.2026.100797","url":null,"abstract":"<div><div>The geothermal project at the VITO Sustainability Park in Mol targets the fractured carbonates of the Dinantian formation. During balanced geothermal operations, several earthquakes were recorded, with a maximum magnitude of M<sub>L</sub> 2.2. To better understand the mechanisms driving this seismicity, we developed a thermo-hydro-mechanical model to simulate pressure, temperature and stress changes on a fault near the injection well, which hosts most of the seismic events. Given the observations of a low stress drop and low seismic moment release, the fault is represented in the model as comprising a few isolated asperities embedded within a broader aseismic zone. Although the model geometry is simplified, and both flow and mechanical behavior are not fully constrained, it shows potential to reproduce the main characteristics of field observations of seismicity at the geothermal site. Our simulations indicate that thermal effects had limited influence on fault stress, primarily due to the relatively small injected volumes. Rate effects - through rapid poroelastic unloading immediately after shut-in – may have facilitated seismogenic slip after shut-in. Aseismic slip, primarily driven by pressure increases, appears to have played a significant role in fault reactivation. The model results suggest that stress transfer from aseismic slip to fault asperities may have been a key driver of seismicity, particularly for larger events occurring at greater depths and farther from the injection well.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"45 ","pages":"Article 100797"},"PeriodicalIF":3.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The low penetration rate is one of the limitations of ultra-deep well drilling, which usually results from the high strength of formation rock with high in-situ stress. The shock-assisted-drilling technique has been proven to be effective in improving the penetration rate of deep rock; however, the fragmentation mechanism is still not clear. Benefiting from the advantages of Peridynamics in simulating crack-involved problems, this paper first introduces the concepts of ordinary state-based Peridynamics and the nonlocal plastic deformation. Then, the nonlocal strain rate effect is reconstructed by reformulating the Peridynamic constitutive relations with the Johnson-Cook model, and the numerical algorithm is developed subsequently. The strain rate effect of yield strength is then validated by solving a benchmark example of uniaxial loading; the stress-strain relation subjected to different load rates is generated. To further investigate the fragmentation under different load rates, the crack propagation of the Brazilian Disk subjected to the Split Hopkinson test is simulated. The crack propagation simulation of BD with/without a slot is consistent with the experiment results. Furthermore, the research systematically reveals the coupling influence of cutter impact and in-situ stress on rock damage evolution and plastic deformation. The numerical simulation demonstrates the stress regulation and damage suppression effects of cutter impact under different in-situ stresses. The dynamic behavior of the rock exhibits a strain-rate-strengthening characteristic and shows a positive correlation between yield strength and strain rate. These findings elucidated the damage evolution mechanism of deep formation rock under impact loads.
{"title":"Peridynamic simulation of deep rock fragmentation subjected to cutter impact with Johnson-Cook model","authors":"Jingkai Chen, Dong Jiang, Zhangcong Huang, Xiaomin Zhang","doi":"10.1016/j.gete.2026.100789","DOIUrl":"10.1016/j.gete.2026.100789","url":null,"abstract":"<div><div>The low penetration rate is one of the limitations of ultra-deep well drilling, which usually results from the high strength of formation rock with high in-situ stress. The shock-assisted-drilling technique has been proven to be effective in improving the penetration rate of deep rock; however, the fragmentation mechanism is still not clear. Benefiting from the advantages of Peridynamics in simulating crack-involved problems, this paper first introduces the concepts of ordinary state-based Peridynamics and the nonlocal plastic deformation. Then, the nonlocal strain rate effect is reconstructed by reformulating the Peridynamic constitutive relations with the Johnson-Cook model, and the numerical algorithm is developed subsequently. The strain rate effect of yield strength is then validated by solving a benchmark example of uniaxial loading; the stress-strain relation subjected to different load rates is generated. To further investigate the fragmentation under different load rates, the crack propagation of the Brazilian Disk subjected to the Split Hopkinson test is simulated. The crack propagation simulation of BD with/without a slot is consistent with the experiment results. Furthermore, the research systematically reveals the coupling influence of cutter impact and in-situ stress on rock damage evolution and plastic deformation. The numerical simulation demonstrates the stress regulation and damage suppression effects of cutter impact under different in-situ stresses. The dynamic behavior of the rock exhibits a strain-rate-strengthening characteristic and shows a positive correlation between yield strength and strain rate. These findings elucidated the damage evolution mechanism of deep formation rock under impact loads.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"45 ","pages":"Article 100789"},"PeriodicalIF":3.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-01-02DOI: 10.1016/j.gete.2025.100785
A.V. Valov , E.V. Dontsov , F. Zhang
Well integrity is a critical challenge in carbon capture and storage (CCS) projects, where debonding of cement sheath can form preferential pathways for CO leakage. This study introduces a numerical framework for simulating fluid-driven debonding along the cement interfaces during CO injection. A pseudo-3D fracture propagation model, adapted to cylindrical well geometry, is coupled with a thermoporoelastic finite element mechanical model of the composite casing-cement-formation system. The framework accounts for poroelastic material behavior, thermal stresses, variations in fluid pressure and temperature, in-situ stress anisotropy, formation layering, and initial stress states induced by well construction and cement hydration. Fracture propagation is simulated in both vertical and circumferential directions, incorporating the effects of buoyancy, fluid viscosity, interfacial adhesion strength, and pressure-dependent leak-off. Numerical results reveal three distinct debonding regimes: crescent-shaped partial debonding, large incomplete debonding with non-monotonic aperture, and complete debonding that is characterized by a fully open channel around the circumference of the well. Sensitivity analysis reveals that debonding evolution is strongly influenced by cement shrinkage, injection conditions, cold fluid effects, and changes in reservoir stress over time. The model provides a predictive tool for assessing leakage risk and fracture evolution under varying cementing conditions, injection scenarios, and reservoir stress states.
{"title":"Thermoporoelastic model for fluid-driven debonding of cement during CO2 injection in a vertical well","authors":"A.V. Valov , E.V. Dontsov , F. Zhang","doi":"10.1016/j.gete.2025.100785","DOIUrl":"10.1016/j.gete.2025.100785","url":null,"abstract":"<div><div>Well integrity is a critical challenge in carbon capture and storage (CCS) projects, where debonding of cement sheath can form preferential pathways for CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> leakage. This study introduces a numerical framework for simulating fluid-driven debonding along the cement interfaces during CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> injection. A pseudo-3D fracture propagation model, adapted to cylindrical well geometry, is coupled with a thermoporoelastic finite element mechanical model of the composite casing-cement-formation system. The framework accounts for poroelastic material behavior, thermal stresses, variations in fluid pressure and temperature, in-situ stress anisotropy, formation layering, and initial stress states induced by well construction and cement hydration. Fracture propagation is simulated in both vertical and circumferential directions, incorporating the effects of buoyancy, fluid viscosity, interfacial adhesion strength, and pressure-dependent leak-off. Numerical results reveal three distinct debonding regimes: crescent-shaped partial debonding, large incomplete debonding with non-monotonic aperture, and complete debonding that is characterized by a fully open channel around the circumference of the well. Sensitivity analysis reveals that debonding evolution is strongly influenced by cement shrinkage, injection conditions, cold fluid effects, and changes in reservoir stress over time. The model provides a predictive tool for assessing leakage risk and fracture evolution under varying cementing conditions, injection scenarios, and reservoir stress states.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"45 ","pages":"Article 100785"},"PeriodicalIF":3.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-01-29DOI: 10.1016/j.gete.2026.100796
Stephen Pansino, Manuel A. Florez, Rafael Torres
Hydraulic fractures propagate in a form that depends on the forces acting on it, including the elastic forces of the rock, the viscous forces of the liquid, and the driving pressure gradient. Rock layering also needs to be accounted for, in which the rock properties can cause sharp changes in these forces. These factors influence the resulting surface area of a fracture, and therefore in the case of EGS, the ultimate productivity of a plant. The rising importance of EGS, and associated costs of drilling, bring a need for high quality models of fracture propagation, in order to assess plant productivity beforehand. We numerically simulate fracture propagation for a field site in the Llanos basin in Colombia, which has a monzogranite basement rock and overlying layers of sandstone and mudstone. We vary the fracture dip between models and keep the other parameters (material properties, injection rate, etc.) constant. Horizontally dipping fractures propagate radially and maintain a circular, penny-shape. Fractures with greater dips become vertically elongated due buoyancy forces, driving the propagation upwards. Fractures that propagate into overlying (softer) rock layers respond by reducing in horizontal breadth. We then assess the heat conduction into the fractures using 3D finite element modeling. Steeply-dipping fractures have larger surface areas (favorable for heat capture), but also propagate upwards into cooler rock. Horizontal fractures have smaller surface areas but remain at depth, in contact with hotter rock. There is a trade-off between these competing factors, so that fractures with dips of 30° maximize the heat capture. For the extensional tectonic environment of this site, we argue that a vertical fracture is likeliest to form. Therefore, in order for an EGS plant to be sufficiently productive, we recommend drilling an injection well that is deep enough to account for the upwards propagation of such a fracture, around 4 km depth.
{"title":"Modeling fracture growth for EGS in foreland sedimentary basins","authors":"Stephen Pansino, Manuel A. Florez, Rafael Torres","doi":"10.1016/j.gete.2026.100796","DOIUrl":"10.1016/j.gete.2026.100796","url":null,"abstract":"<div><div>Hydraulic fractures propagate in a form that depends on the forces acting on it, including the elastic forces of the rock, the viscous forces of the liquid, and the driving pressure gradient. Rock layering also needs to be accounted for, in which the rock properties can cause sharp changes in these forces. These factors influence the resulting surface area of a fracture, and therefore in the case of EGS, the ultimate productivity of a plant. The rising importance of EGS, and associated costs of drilling, bring a need for high quality models of fracture propagation, in order to assess plant productivity beforehand. We numerically simulate fracture propagation for a field site in the Llanos basin in Colombia, which has a monzogranite basement rock and overlying layers of sandstone and mudstone. We vary the fracture dip between models and keep the other parameters (material properties, injection rate, etc.) constant. Horizontally dipping fractures propagate radially and maintain a circular, penny-shape. Fractures with greater dips become vertically elongated due buoyancy forces, driving the propagation upwards. Fractures that propagate into overlying (softer) rock layers respond by reducing in horizontal breadth. We then assess the heat conduction into the fractures using 3D finite element modeling. Steeply-dipping fractures have larger surface areas (favorable for heat capture), but also propagate upwards into cooler rock. Horizontal fractures have smaller surface areas but remain at depth, in contact with hotter rock. There is a trade-off between these competing factors, so that fractures with dips of 30° maximize the heat capture. For the extensional tectonic environment of this site, we argue that a vertical fracture is likeliest to form. Therefore, in order for an EGS plant to be sufficiently productive, we recommend drilling an injection well that is deep enough to account for the upwards propagation of such a fracture, around 4 km depth.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"45 ","pages":"Article 100796"},"PeriodicalIF":3.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146173571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-20DOI: 10.1016/j.gete.2025.100782
Boran Huang , Jin Zhang , Qi-Zhi Zhu , Lunyang Zhao , Sili Liu
A temperature-dependent micromechanical creep–damage constitutive model is proposed within the framework of irreversible thermodynamics and homogenization theory to investigate the long-term thermo-mechanical behavior of quasi-brittle rocks. The model explicitly couples frictional sliding and microcrack propagation as the dominant modes of energy dissipation, where the friction coefficient, critical damage resistance, and damage threshold are expressed as temperature-dependent functions. Subcritical crack growth is incorporated to capture time-dependent damage accumulation and strain development. Model validation is conducted against triaxial thermo-creep experiments on gneissic granite, deep coals, and Beishan granite. The simulations reproduce the complete creep evolution – primary, secondary (steady-state), and tertiary (accelerated) stages – with relatively few parameters. The results clarify the role of creep rate—controlling factors, reveal the mechanisms of damage evolution and strain-rate acceleration under elevated temperatures, and demonstrate the promoting effect of thermal loading on energy dissipation. This unified framework not only advances the understanding of rock creep under coupled thermal–mechanical fields but also provides a theoretical basis for assessing the long-term thermal stability and reliability of deep underground engineering structures.
{"title":"Micromechanical modeling of long-term creep behavior of quasi-brittle rocks considering thermo-mechanical coupling effects","authors":"Boran Huang , Jin Zhang , Qi-Zhi Zhu , Lunyang Zhao , Sili Liu","doi":"10.1016/j.gete.2025.100782","DOIUrl":"10.1016/j.gete.2025.100782","url":null,"abstract":"<div><div>A temperature-dependent micromechanical creep–damage constitutive model is proposed within the framework of irreversible thermodynamics and homogenization theory to investigate the long-term thermo-mechanical behavior of quasi-brittle rocks. The model explicitly couples frictional sliding and microcrack propagation as the dominant modes of energy dissipation, where the friction coefficient, critical damage resistance, and damage threshold are expressed as temperature-dependent functions. Subcritical crack growth is incorporated to capture time-dependent damage accumulation and strain development. Model validation is conducted against triaxial thermo-creep experiments on gneissic granite, deep coals, and Beishan granite. The simulations reproduce the complete creep evolution – primary, secondary (steady-state), and tertiary (accelerated) stages – with relatively few parameters. The results clarify the role of creep rate—controlling factors, reveal the mechanisms of damage evolution and strain-rate acceleration under elevated temperatures, and demonstrate the promoting effect of thermal loading on energy dissipation. This unified framework not only advances the understanding of rock creep under coupled thermal–mechanical fields but also provides a theoretical basis for assessing the long-term thermal stability and reliability of deep underground engineering structures.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"45 ","pages":"Article 100782"},"PeriodicalIF":3.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145841755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-01-14DOI: 10.1016/j.gete.2026.100791
Marcelo Menezes Farias , Ivens da Costa Menezes Lima , Francisco Marcondes , Kamy Sepehrnoori
This work presents an unstructured grid-based formulation for compositional reservoir simulation coupled with elastic, elastoplastic, and viscoplastic geomechanical models. Implemented in the UTCOMPRS simulator using the Element-based Finite Volume Method (EbFVM), the proposed approach explicitly solves both flow and mechanical equations on unstructured grids. It supports nonlinear models, such as Mohr-Coulomb, Drucker-Prager, and a Perzyna-based viscoplastic criterion to represent material yield. Five case studies are conducted to verify the geomechanical implementation: Prandtl’s benchmark validates the plastic and viscoplastic models; primary production matched results from a commercial simulator; WAG injection and CO2 storage cases demonstrated the influence of the geomechanical model on production forecast, reservoir pressure, and rock deformation; and a Pre-Salt reservoir proxy tested computational efficiency, and numerical accuracy of the EbFVM across multiple grid refinements. Results show that the EbFVM captures nonlinear deformation while delivering solutions comparable to fine meshes using significantly coarser grids. The proposed formulation provides a robust and versatile tool for simulating complex reservoir-geomechanical problems.
{"title":"A unified Element-based Finite Volume Method for linear and nonlinear geomechanics and compositional reservoir simulation","authors":"Marcelo Menezes Farias , Ivens da Costa Menezes Lima , Francisco Marcondes , Kamy Sepehrnoori","doi":"10.1016/j.gete.2026.100791","DOIUrl":"10.1016/j.gete.2026.100791","url":null,"abstract":"<div><div>This work presents an unstructured grid-based formulation for compositional reservoir simulation coupled with elastic, elastoplastic, and viscoplastic geomechanical models. Implemented in the UTCOMPRS simulator using the Element-based Finite Volume Method (EbFVM), the proposed approach explicitly solves both flow and mechanical equations on unstructured grids. It supports nonlinear models, such as Mohr-Coulomb, Drucker-Prager, and a Perzyna-based viscoplastic criterion to represent material yield. Five case studies are conducted to verify the geomechanical implementation: Prandtl’s benchmark validates the plastic and viscoplastic models; primary production matched results from a commercial simulator; WAG injection and CO<sub>2</sub> storage cases demonstrated the influence of the geomechanical model on production forecast, reservoir pressure, and rock deformation; and a Pre-Salt reservoir proxy tested computational efficiency, and numerical accuracy of the EbFVM across multiple grid refinements. Results show that the EbFVM captures nonlinear deformation while delivering solutions comparable to fine meshes using significantly coarser grids. The proposed formulation provides a robust and versatile tool for simulating complex reservoir-geomechanical problems.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"45 ","pages":"Article 100791"},"PeriodicalIF":3.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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